 class A {

}

class B extends A{
	
}

class C extends B{
	
}

public class Test{
	public static void main(String[] args) {
		A a = new C();
		//向下转型
		B b = (B)a;
		
		C c = (C)a;
		if (a instanceof B) {
			
		}
		
		
		System.out.println("正确运行");
	}
}
